Vibratory system for a compactor

ABSTRACT

A vibratory system for a compactor is provided. The vibratory system has a first eccentric, a second eccentric, and a drive shaft. The second eccentric is rotatably and coaxially positioned with respect to the first eccentric. The drive shaft is rotatably coupled to the second eccentric and rotatably coupled to the first eccentric through a helical spline.

CLAIM FOR PRIORITY

The present application claims priority from U.S. ProvisionalApplication Ser. No. 61/291,701, filed Dec. 31, 2009, which is fullyincorporated herein.

TECHNICAL FIELD

This disclosure relates to a vibratory system for a compactor machine,and more particularly, to a variable amplitude vibratory system for acompactor machine.

BACKGROUND

Vibratory compactor machines are frequently used to compact freshly laidasphalt, soil, and other compactable materials. These compactor machinesmay include plate type compactors or rotating drum compactors with oneor more drums. The drum-type compactor compacts the material over whichthe machine is driven. In order to compact the material, the drumassembly includes a vibratory mechanism including inner and outereccentric weights arranged on a rotatable shaft within the interiorcavity of the drum, for inducing vibrations on the drum.

The amplitude and frequency of the vibratory forces determine the degreeof compaction of the material, and the speed and efficiency of thecompaction process. The amplitude of the vibration forces is changed byaltering the position of a pair of weights with respect to each other.The frequency of the vibration forces is managed by controlling thespeed of a drive motor in the compactor drum.

The required amplitude of the vibration force may vary depending on thecharacteristics of the material being compacted. For instance, highamplitude works best on thick lifts or soft materials, while lowamplitude works best on thin lifts and harsh mixes. Amplitude variationis important because different materials require different levels ofcompaction. Moreover, a single compacting process may require differentamplitude levels because higher amplitude may be required at thebeginning of the process, and the amplitude may be gradually lowered asthe process is completed.

Conventional vibratory compactor machines are problematic in that theamplitude and frequency of the vibration force can only be set tocertain predetermined levels, or the mechanisms for adjusting thevibration amplitude are complex. One such vibratory mechanism isdisclosed in U.S. Pat. No. 4,350,460 issued to Lynn A. Schmelzer et al.on Sep. 21, 1982 and assigned to the Hyster Company.

The present disclosure is directed to overcome one or more of theproblems as set forth above.

SUMMARY

In one aspect of the present disclosure, a vibratory system for acompactor is provided. The vibratory system has a first eccentric, asecond eccentric, and a drive shaft. The second eccentric is rotatablyand coaxially positioned with respect to the first eccentric. The driveshaft is rotatably coupled to the second eccentric and rotatably coupledto the first eccentric.

In another aspect of the present disclosure, a compactor is provided.The compactor has a drum and a vibratory system. The drum has a drumaxis. The vibratory system is rotatably positioned within the drum aboutthe drum axis and has a first eccentric, a second eccentric, and a driveshaft. The second eccentric is rotatably and coaxially positioned withrespect to the first eccentric. The drive shaft is rotatably coupled tothe second eccentric and rotatably coupled to the first eccentric.

In a third aspect of the present disclosure, a method of providing avibratory system for a compactor is provided. The method includes thestep of providing a first eccentric, a second eccentric, and a driveshaft. The method also includes the steps of rotatably and coaxiallypositioning the second eccentric with respect to the first eccentric,and the step of rotatably coupling the drive shaft to the secondeccentric. The method includes the step of rotatably coupling the driveshaft to the first eccentric.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a side elevation view of a machine embodying the presentdisclosure;

FIG. 2 shows an axial cross section view taken along the line 2-2through a compacting drum of the machine of FIG. 1, showing anembodiment of the present disclosure;

FIG. 3 is a detail view of the vibratory mechanism of FIG. 2, with theeccentric shown at the maximum amplitude position; and

FIG. 4 is a detail view of the vibratory mechanism of FIG. 2, with theeccentric shown at the minimum amplitude position.

DETAILED DESCRIPTION

FIG. 1 illustrates a machine 10 for increasing the density of acompactable material or mat 12 such as soil, gravel, or bituminousmixtures. The machine 10 is, for example, a double drum vibratorycompactor, having a front or first compacting drum 14 and a rear orsecond compacting drum 16 rotatably mounted on a main frame 18 about adrum axis 19 (seen in FIG. 2), although compactors having only a singledrum may also be used without departing from the present disclosure. Themain frame 18 also supports an engine 20 that supplies power to at leastone power source 22, 24. Electrical generators or fluid pumps, such asvariable displacement fluid pumps, may be used as interchangeablealternatives for power sources 22, 24 without departing from the presentdisclosure.

As the front drum 14 and the rear drum 16 are structurally andoperatively similar, the description, construction and elementscomprising the front drum 14 will now be discussed in detail and appliesequally to the rear drum 16.

As seen in FIG. 2, the front drum 14 is shown in a split drumconfiguration. Those skilled in the art will recognize that front drum14 could also be in a solid drum configuration without departing fromthe scope and spirit of this disclosure. Notwithstanding, front drum 14includes a split 15 that separates front drum 14 into a first and asecond drum section 30, 32, a first and a second propel motor 42, 44, apair of offset gearboxes 46, a support arrangement 50, and a vibratorysystem 90. Each of the first and second drum sections 30, 32 is made upof an outer shell 34 that is manufactured from a steel plate that isrolled and welded at the joining seam. A first bulkhead 36 is fixedlysecured to the inside diameter of the outer shell 34 of the first drumsection 30 as by welding and a second bulkhead 38 is fixedly secured tothe inside diameter of the outer shell 34 of the second drum section 32in the same manner. The first and second drum sections 30, 32 arevibrationally isolated from the main frame 18 by rubber mounts (notshown).

The first and the second propel motors 42, 44 are positioned between themain frame 18 and the first and the second drum sections 30, 32,respectively. For example, the first and second propel motors 42, 44 areeach connected to a mounting plate (not shown) secured to the main frame18 via rubber mounts (not shown). The output of the first and secondpropel motors 42, 44 are connected to the first and the second bulkheads36, 38, respectively, through a pair of offset gearboxes 46. The offsetgearboxes 46 allow the first and second propel motors 42, 44 to bepositioned offset from the drum axis 19. With a different mountingconfiguration or motor arrangement, the first and second propel motorsmay be directly connected to the first and second bulkheads 36, 38,eliminating the offset gearboxes 46. The first and second propel motors42, 44 are operatively connected to the power source 22, 24, whichsupplies a pressurized operation fluid or electrical current to thefirst and second propel motors 42, 44 for propelling the first andsecond drum section 30, 32.

The support arrangement 50 rotatably connects the first drum section 30to the second drum section 32 and houses a vibratory mechanism 100 ofthe vibratory system 90 within a housing 58. The support arrangement 50is rotatably connected between the first and second bulkheads 36, 38 toenable the first and second drum section 30, 32 to rotate in relation toone another. The support arrangement 50 includes a first support member52 and a second support member 54. The first support member 52 isconnected to the first bulkhead 36, while the second support member 54,being made up of two separate pieces connected by fasteners, isconnected to the second bulkhead 38. Although the second support member54 as shown in this embodiment is made of two separate pieces, it mayalso be one complete piece. The first support member 52 is rotatablypositioned inside the second support member 54 and rotatably connectedby a bearing arrangement 56. In this case, the bearing arrangementconsists of tapered roller bearings. The support arrangement 50 allowsthe first propel motor 42 to rotate the first drum section 30 about thedrum axis 19 at either the same rate or at a different rate than thesecond propel motor 44 rotates the second drum section 32 about the drumaxis 19.

Of course, this is but one of a number of arrangements that the supportarrangement 50 may assume. For example, the second support member 54 maybe rotatably positioned outside the first support member 52. The firstsupport member 52 may also be rotatably positioned outside the secondsupport member 54. Another example may have the first and second supportmembers 52, 54 come together at the bearing arrangement 56 where theymay be rotatably connected without any overlap of the first and secondsupport members 52, 54. Additionally, the bearing arrangement 56 thatmay be seen in any of the embodiments may comprise, but is not limitedto, tapered roller bearings, ball bearings, and bronze bushings.

The vibratory system 90 includes the vibratory mechanism 100, avibratory motor 110, a drive shaft 118, and a linear actuator 150. Thevibratory mechanism 100 is rotatably supported about the drum axis 19within the housing 58 with a plurality of bearings 170. The bearings 170may be cylindrical roller bearings, although other types of bearings orbushings may also be used. In order to provide lubrication and coolingto the vibratory mechanism 100, the housing 58 may be filled with oil. Alip seal 176 may be positioned at the ends of the housing 58 to keep theoil within the housing 58 and dirt and debris out of the housing 58.

Referring now to FIGS. 3-4, the vibratory mechanism 100 is driven by thevibratory motor 110 through the drive shaft 118, and includes an outereccentric 120, an inner eccentric 130, and a key shaft 140. Thevibratory motor 110 may be a hydraulic or electric motor and may bemounted to the machine 10 through a mounting plate (not shown) that issecured to the main frame 18 via rubber mounts (not shown). Alternately,the vibratory motor 110 may be mounted to the main frame through someother way known in the art, such as by mounting the vibratory motor 110to one of the offset gearboxes 46 through a flange 112. The vibratorymotor 110 is rotationally coupled to the drive shaft 118 through anadapter 114 with a speed sensor 116. The speed sensor 116 is atachometer and may include a toothed ring and pickup, a magnetic sensor,or any other technique known in the art. The vibratory motor 110 may bedriven by one of the power sources 22, 24, or by another power source(not shown).

The outer eccentric 120 is shown as a three-piece assembly with a driveside stub shaft 121, a helical side stub shaft 122, and a lobe 126. Thedrive shaft 118 is attached to the drive side stub shaft 121 via asplined connection or other technique known in the art. The bearings 170may be attached to the outside of stub shafts 121, 122. The drive sidestub shaft 121 and the helical side stub shaft 122 are attached to thelobe 126 via bolts or some other known technique. The lobe 126 mayformed as a hollow semi-cylindrical or lobed casting having an axis ofrotation and with more weight on one radial side than on the other. Thehelical side stub shaft 122 also includes a helical bore 124, which willbe described in detail below.

The inner eccentric 130 is positioned within the outer eccentric 120 andis rotatably supported about the drum axis 19 with a pair of bearings172, which may be tapered roller bearings, ball bearings, or bushingssuch as bronze bushings. Bearings 172 are positioned within the stubshafts 121, 122. The inner eccentric 130 may be a solid semi-cylindricalor lobed casting with more weight on one radial side than on the other.The inner eccentric 130 also includes a bore 132. The bore 132 is formedwith one or more splines that extend axially parallel to the drum axis19. Alternately, the bore 132 may be formed with an axially-extendingkeyway (not shown).

The key shaft 140 has an axial splined portion 142 at one end, a smoothportion 144 in the middle, and a helical splined portion 146 at theother end. The axial splined portion 142 engages with the bore 132 ofthe inner eccentric 130 such that the inner eccentric 130 and the keyshaft 140 are rotatably fixed with respect to each other. However, thekey shaft 140 may still slide axially into the bore 132 of the innereccentric 130. In one embodiment, the axial splined portion 142 mayinclude 18 straight splined teeth, although other numbers of teeth maybe used depending on the application. The helical splined portion 146engages with the helical bore 124 of the outer eccentric 120 to transferthe linear motion of the key shaft 140 into rotational motion of boththe key shaft 140 and inner eccentric 130. The helical splined portion146 and the helical bore 124 may include helical splines with a splineangle of approximately 60 degrees to slightly less than 90 degrees fromthe drum axis 19, although any spline angle that permits the linearmotion of the key shaft 140 to be transferred to rotational motion ofthe key shaft 140 may also be used.

The linear actuator 150 has an axially extending rod 152 that engagesthe key shaft 140. The linear actuator 150 has an extension stroke wherethe rod 152 extends out from the linear actuator 150, and a retractionstroke where rod 152 retracts into the linear actuator 150. As the rod152 extends along the drum axis 19, it pushes the key shaft 140 alongthe drum axis 19. This linear motion is then converted into rotationalmotion of the key shaft 140 and inner eccentric 130 with the helicalspline interface between the helical bore 124 and the helical splinedportion 146. The linear actuator 150 may be a hydraulic or electricactuator and may be mounted to the machine 10 through a mounting plate(not shown) that is secured to the main frame 18 via rubber mounts (notshown). Alternately, the linear actuator 150 may be mounted to the mainframe 18 through some other way known in the art, such as by mountingthe linear actuator 150 to one of the offset gearboxes 46 through aflange 154. The linear actuator 150 may be driven by one of the powersources 22, 24, or by another power source (not shown). The rod 152 mayengage the key shaft 140 through an adapter 180. The adapter 180 may bemounted to the key shaft 140 through a bearing 174 and may also includea physical stop such as a set screw or key (not shown) for the outerrace of the bearing 174 and/or the rod 152. The physical stop serves toprevent the rod 152 from rotating at the same rate as the key shaft 140,which in turn rotates at the same rate as the vibratory motor 110. Theseals of the linear actuator 150 may not be able to handle the high rateof speeds of the vibratory motor 110, which may exceed 3800 revolutionsper minute. The linear actuator 150 also includes a position sensor 156,which senses the linear extension of the rod 152 along the drum axis 19.

FIG. 3 shows the vibratory mechanism 100 with the outer eccentric 120and inner eccentric 130 in phase with each other about the drum axis 19.When the outer and inner eccentrics 120, 130 are in phase and rotated bythe vibratory motor 110, the drum 14 produces a maximum amplitude. FIG.4 shows the vibratory mechanism 100 with the outer eccentric 120 and theinner eccentric 130 180 degrees out of phase with each other about thedrum axis 19. When the outer and inner eccentrics 120, 130 are 180degrees out of phase and rotated by the vibratory motor 110, the drum 14produces a minimum amplitude.

When the outer and inner eccentrics 120, 130 are 180 degrees out ofphase, as seen in FIG. 4, a radial alignment hole 128 in the lobe 126 ofthe outer eccentric 120 aligns with a similar radial alignment hole 138in the inner eccentric 130. Due to tolerance stack-up in the manufactureof the vibratory mechanism 100, these alignment holes 128, 138, incombination with a clamp-nut 160, allow the vibratory mechanism 100 tobe calibrated. When the outer and inner eccentrics 120, 130 are out ofphase with each other, a rod (not shown) may be inserted into bothradial alignment holes 128, 138. The clamp-nut 160 is then placed overthe key shaft 140, butted up against the helical side stub shaft 122,and locked onto the key shaft 140. If the minimum extension position ofrod 152 is used to define the maximum amplitude (as seen in FIG. 3), theclamp-nut 160 provides a physical stop for the extension of rod 152 forthe minimum amplitude. Note that the alignment holes 128, 138 mayalternately be positioned in the outer and inner eccentrics 120, 130such that they align when they are in phase, at the maximum amplitude.In such a case, the physical interference of clamp-nut 160 against thehelical side stub shaft 122 would indicate the maximum amplitude, and aminimum extension of rod 152 would represent the minimum amplitude.

INDUSTRIAL APPLICABILITY

The disclosed vibratory mechanism and drum for a machine may be used toprovide a variably adjustable amplitude ranging from a maximum to aminimum for any compactor machine. In one exemplary embodiment, thevibratory mechanism is for a vibratory compactor, such as a double splitdrum asphalt compactor.

In operation, as the machine 10 is driven over the compactable material12, the frequency and amplitude of the vibratory system 90 may bemanually controlled by an operator or automatically controlled by anintelligent compaction system. The frequency of impacts may becontrolled by increasing or decreasing the speed of the vibratory motor110, with feedback from the speed sensor 116. The amplitude of theimpacts may be controlled by brining the inner eccentric 130 in phase orout of phase with the outer eccentric 120. Starting from a maximumamplitude position as depicted in FIG. 3, the rod 152 of the linearactuator 150 may be extended. As the rod 152 is extended, the key shaft140, which is rotatably secured to the inner eccentric 130, is pushedalong the drum axis 19 into the straight splines of bore 132 of theinner eccentric 130. The helical spline interface between the helicalbore 124 and the helical splined portion 146 converts the linear motionof the key shaft 140 and rod 152 into rotational movement of the innereccentric 130 with respect to the outer eccentric 120. When the innereccentric 130 and outer eccentric 120 are 180 degrees out of phase witheach other, a position of minimum amplitude has been reached, and theclamp-nut 160 provides a physical stop for the further extension of rod152. Similarly, the amplitude of the vibratory system 90 may bedecreased by retracting the rod 152 into the linear actuator 150, movingfrom the position of FIG. 4 to the position shown in FIG. 3.Intermediate amplitudes less than the maximum or greater than theminimum may be obtained by setting the phase angle of the innereccentric 130 to the outer eccentric 120 between 0 and 180 degrees. Theposition sensor 156 may be used to provide feedback to an operator via adisplay or to the intelligent compaction system.

While the disclosure has been described with reference to details of theillustrated embodiments, these details are not intended to limit thescope of the disclosure as defined in the appended claims. For example,the vibratory motor may be coupled to the inner eccentric and the linearactuator may be coupled to the outer eccentric. Other aspects, objectsand advantages of this disclosure can be obtained from a study of thedrawings, the disclosure, and the appended claims.

1. A vibratory system for a compactor, comprising: a first eccentric; asecond eccentric rotatably and coaxially positioned with respect to thefirst eccentric; and a key shaft rotatably coupled to the secondeccentric and rotatably coupled to the first eccentric.
 2. The vibratorysystem of claim 1, wherein the key shaft comprises an axial splineportion; a helical spline portion, and wherein the first eccentric isrotatably coupled to the first eccentric through the helical splineportion.
 3. The vibratory system of claim 2, further comprising: anactuator having an extension and a retraction stroke and coupled to thekey shaft, and wherein the second eccentric rotates in a first angulardirection with respect to the first eccentric on the extension strokeand rotates in a second angular direction opposite the first angulardirection with respect to the first eccentric on the retraction stroke.4. The vibratory system of claim 3, further comprising: an adaptercoupling the actuator to the key shaft, the adapter including at leastone bearing.
 5. The vibratory system of claim 2, wherein the secondeccentric is positioned within the first eccentric.
 6. The vibratorysystem of claim 5, wherein the axial portion of the key shaft slideswithin the second eccentric.
 7. The vibratory system of claim 5, furthercomprising: an actuator having an extension and a retraction stroke andcoupled to the key shaft, and wherein the second eccentric rotates in afirst angular direction with respect to the first eccentric on theextension stroke and rotates in a second angular direction opposite thefirst angular direction with respect to the first eccentric on theretraction stroke, wherein the first and the second eccentric each havea radial alignment hole, and the axes of the radial alignment holesalign when the first eccentric and the second eccentric are in phase. 8.The vibratory system of claim 5, further comprising: an actuator havingan extension and a retraction stroke and coupled to the key shaft, andwherein the second eccentric rotates in a first angular direction withrespect to the first eccentric on the extension stroke and rotates in asecond angular direction opposite the first angular direction withrespect to the first eccentric on the retraction stroke, wherein thefirst and the second eccentric each have a radial alignment hole, andthe axes of the radial alignment holes align when the first eccentricand the second eccentric are 180 degrees out of phase.
 9. The vibratorysystem of claim 2, wherein the first eccentric has a helical bore andfurther comprising: a helical screw positioned in the helical bore andcoupled to the key shaft, the helical spline positioned on the helicalscrew.
 10. The vibratory system of claim 2, further comprising: a motorcoupled to the first eccentric and configured to rotate the firsteccentric about an axis.
 11. The vibratory system of claim 2, furthercomprising: a motor coupled to the second eccentric and configured torotate the second eccentric about an axis.
 12. A compactor, comprising:a drum having a drum axis; and a vibratory system rotatably positionedwithin the drum about the drum axis and having: a first eccentric; asecond eccentric rotatably and coaxially positioned with respect to thefirst eccentric; and a key shaft rotatably coupled to the secondeccentric and rotatably coupled to the first eccentric through a helicalspline.
 13. The compactor of claim 12, wherein the key shaft comprisesan axial spline portion; a helical spline portion; and wherein the firsteccentric is rotatably coupled to the first eccentric through thehelical spline portion.
 14. The compactor of claim 13, wherein thevibratory system further includes: an actuator having an extension and aretraction stroke and coupled to the key shaft, and wherein the secondeccentric rotates in a first angular direction with respect to the firsteccentric on the extension stroke and the second eccentric rotates in asecond angular direction opposite the first angular direction withrespect to the first eccentric on the retraction stroke.
 15. Thecompactor of claim 12, wherein the vibratory system further includes: anadapter coupling the actuator to the key shaft, the adapter including atleast one bearing.
 16. The compactor of claim 12, wherein the secondeccentric is positioned within the first eccentric.
 17. The compactor ofclaim 16, wherein the axial portion of the key shaft slides within thesecond eccentric.
 18. The compactor of claim 16, wherein the vibratorysystem further includes: an actuator having an extension and aretraction stroke and coupled to the key shaft, and wherein the secondeccentric rotates in a first angular direction with respect to the firsteccentric on the extension stroke and rotates in a second angulardirection opposite the first angular direction with respect to the firsteccentric on the retraction stroke, and wherein the first and the secondeccentric each have a radial alignment hole, and the axes of the radialalignment holes align when the first eccentric and the second eccentricare in phase.
 19. The compactor of claim 16, wherein the vibratorysystem further includes: an actuator having an extension and aretraction stroke and coupled to the key shaft, and wherein the secondeccentric rotates in a first angular direction with respect to the firsteccentric on the extension stroke and rotates in a second angulardirection opposite the first angular direction with respect to the firsteccentric on the retraction stroke, and wherein the first and the secondeccentric each have a radial alignment hole, and the axes of the radialalignment holes align when the first eccentric and the second eccentricare 180 degrees out of phase.
 20. The compactor of claim 13, wherein thefirst eccentric has a helical bore and the vibratory system furtherincludes: a helical screw positioned in the helical bore and coupled tothe key shaft, the helical spline positioned on the helical screw. 21.The compactor of claim 13, wherein the vibratory system furtherincludes: a motor coupled to the first eccentric and configured torotate the first eccentric about the drum axis.
 22. The compactor ofclaim 13, wherein the vibratory system further includes: a motor coupledto the second eccentric and configured to rotate the second eccentricabout the drum axis.
 23. A method for providing a vibratory system for acompactor, comprising: providing a first eccentric, a second eccentric,and a key shaft; rotatably and coaxially positioning the secondeccentric with respect to the first eccentric; rotatably coupling thekey shaft to the second eccentric; and rotatably coupling the key shaftto the first eccentric.
 24. The method of claim 23, wherein the keyshaft comprises an axial spline portion; a helical spline portion; andwherein the step of rotatably coupling the key shaft to the firsteccentric is done through the helical spline portion.
 25. The method ofclaim 23, further comprising: coupling a motor to the first eccentric,the motor configured to rotate the first eccentric about an axis; andcoupling an actuator to the key shaft, the actuator having an extensionand a retraction stroke, wherein the second eccentric rotates in a firstangular direction with respect to the first eccentric on the extensionstroke and rotates in a second angular direction opposite the firstangular direction with respect to the first eccentric on the retractionstroke.
 26. The method of claim 23, further comprising: coupling a motorto the second eccentric, the motor configured to rotate the secondeccentric about an axis; and coupling an actuator to the key shaft, theactuator having an extension and a retraction stroke, wherein the secondeccentric rotates in a first angular direction with respect to the firsteccentric on the extension stroke and rotates in a second angulardirection opposite the first angular direction with respect to the firsteccentric on the retraction stroke.